need advice, engine codes P0307, P0302, P0308 so far.
Last summer we purchased a 2006 Grand Marquise with 16K showing (27K now). A month later the CEL came on and the computer showed 12 codes, so I took the car to the local dealer and a month later got it back with$1400.00 worth of new parts that were not needed since they had to replace the computer. Last week the car started missing and the cel came on showing code P0307. Replaced the coil, and plug and the car ran perfect for a day. Next day same thing showing P0302. Same repair ran fine for a day. Yesterday cel throwing code P0308, and will replace coil today. Any idea as to why this is happening? Is there anything that I can check that will make it throw a code for one cylinder at a time like this. When the repair is made the car runs perfect for about 20 miles and the cel comes on after the miss starts. So far it has been on a different cylinder each time.